This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Sat-1 (Slc26a1) is a sodium-independent sulfate anion transporter that operates as an anion exchanger. Sat-1 is a membrane protein that plays a crucial role in intracellular uptake of inorganic sulfate in specific cells, which is then utilized in various metabolic and growth processes. The physiological importance of the sat-1-mediated sulfate reabsorption has been confirmed in experimental chronic renal failure, which is associated with major downregulation of the renal sat-1 expression and significant increase of the fractional sulfate excretion. We have identified multiple bacterial homologues of this family and propose to determine the structure of Sat-1 in order to understand its transport mechanism.